Over a long period of years, most fire hydrants were produced with heavy metal casings of cast iron or the like which were designed to withstand the shock of forces tending to knock them over. When such hydrants were struck by moving vehicles with sufficient force, not only were the hydrants damaged beyond repair, the vehicle also badly damaged, and the occupants of the vehicle often seriously injured, but it was, more often than not, necessary to dig down around the standpipe to the water main so that the damaged standpipe, valve seat, valve, or the like could be repaired or replaced. This meant the hydrant and the main back to the first cutoff valve were out of service for extended periods.
To substantially prevent this damage and reduce repair time, we have developed a fire hydrant having a lower standpipe and a lower section of valve rod extending to substantially ground level. An upper standpipe and an upper section of valve rod are each conncted to their respective lower counterparts in such a manner that they break away under impact from a moving vehicle or the like, thus minimizing the damage to both the upper and lower portions of the hydrant, to the moving impacting vehicle, and to any occupants thereof. By having this breakaway point at substantially the ground surface, and by providing novel means of coupling the upper and lower portions to each other, it is possible to repair the hydrant without digging it up in order to replace the broken parts. Such repairs can often be made in a matter of minutes.
One form of this structure is illustrated and described in our U.S. Pat. No. 3,586,019 for FIRE HYDRANT issued to our assignee, Waterous Company, on June 22, l971.
In hydrants such as those illustrated in our patent, the valve is opened by forcing it straight down against the pressure of the water in the main to open the hydrant to flow of water therethrough, and is closed by drawing up on the valve rod to bring the valve up in contact with its seat so that it can be again held closed by the force of the water in the main and by a valve operating nut assembly and the valve rod. Should excessive force be exerted on the valve operating nut after the valve is firmly in contact with the valve seat, through carelessness or abuse, or because a pebble lodged between the valve and seat, for example, it was possible to break the frangible coupling between the upper and lower valve rod sections. Then the rod sections can become misaligned, and/or, when the valve operating nut is rotated in direction to open the valve, the upper secton of the valve rod can rotate with the operating nut assembly and not descend. In either situation, force would not be exerted on the lower valve rod section, and the valve would not open, thus causing failure of the hydrant for its intended function during an emergency situation, for example.